However, I can blow your comments right out of the water... again. Sorry.

The Subaru Select monitor was on the ground beside the car, and had MULTIPLE cables between it and the actual ECU plug. They didn't look particularly heavy-duty, but were thicker than mine (probably because mine aren't coated in anything to keep all the wires together). If anything, the select monitor is even FURTHER from the ECU than my laptop is.

And for all asking, it matters NOT whether I use internal laptop battery or use my inverter. The result is exactly the same in either case.

Good theories, but sadly not correct.

EDIT: Also, I have another way to prove that the theories are wrong.

The TCU sends coherent data. The TCU is right next to the ECU, and is CLOSER to the engine bay than the ECU, and is FURTHER from the select monitor/laptop than the ECU. I rest my case.